In the field of the present invention, i.e. particularly the field of electric bicycles and related pedal force sensors, there are mechanisms for torque detection, in order to conclude upon the cyclist power with the aid of the torque with which the pedal crank is being actuated. The cyclist power or a comparable quantity is used as an input quantity in the regulation of an electric auxiliary motor of electric bicycles. The sensors used are provided directly at exposed locations and fastened to elements via which the entire torque is transmitted. For this reason, they are particularly prone to error.
Besides solutions in which a force is ascertained directly by detection at the pedal crank shaft or by force sensors situated on the pedals, there are approaches that are in German document DE 698 20 41 T2. In this publication, a phase offset is detected between two wheels which are movable with respect to each other and which have a spring mechanism. However, the detection requires means such as optical or magnetic scanning and goes along with a “soft” drive, in which a torque is converted into a spring motion, instead of into a forward movement. In addition, the data evaluation required is costly.
It is therefore the object of the present invention to provide a simple mechanical system for detecting torque, without having to resort to error-prone or costly precautionary measures.